Living things have no inertia, and tend to no equilibrium.

I do not say think as I think, but think in my way. Fear no shadows, least of all in that great spectre of personal unhappiness which binds half the world to orthodoxy.

Science is simply common sense at its best, that is, rigidly accurate in observation, and merciless to fallacy in logic.

My experience of the world is that things left to themselves don't get right.

A man's worst difficulties begin when he is able to do as he likes.

If individuality has no play, society does not advance; if individuality breaks out of all bounds, society perishes.

A good man: body serves his will and enjoys hard work, clear intellect that understands the truths of nature, full of passion for life but controlled by his will, well-developed conscience, loves beauty in art and nature, despises inferior morality, respects himself and others.